*"Is asking someone who he/she voted for illegal or simply morally wrong?

Would you be uncomfortable sharing this knowledge or would you freely tell who you voted for? (I have Presidential Elections in mind but it really can be any sort of government voting system)"

Michael Peacock, Addito Salis Grano.

In the United States it is neither illegal nor considered immoral by the vast majority to ask. In fact there are people whose job it is to ask voters how they cast their votes as they exit the polling places (exit poll). That's how the news outlets know what to tell you on election night before the ballots have been counted.

What is absolutely illegal and immoral is to violate a person's right to privacy when it comes to voting. You may ask. You may not force a person to disclose.

And this is partly why it is considered by some, including myself, rude to ask, unless you are a pollster as previously mentioned. It's just bad form. Some people don't like talking about their political views. Being respectful includes respecting that. And as Karen pointed out, if someone is interested in talking about it they will; you don't need to ask.

*https://www.quora.com/Is-asking-someone-who-he-she-voted-for-illegal-or-simply-morally-wrong

Illegal? No. Immoral? No. Rude? In most cases, yes. Cheers.